Toothed-wheel gearchange

ABSTRACT

A toothed-wheel gear change with power distribution over several layshafts (6, 7) having a radially and axially supported input shaft (2) and an output shaft (main shaft) (9) which is floating. At least one input gear (3, 4) provided on said input shaft (2) transmits the torque to gears (8) meshing therewith and firmly connected with the layshafts. The loose gears (10) are axially secured but radially free on the input and output shafts. A movable securing device (12, 13) makes possible the radial fixing of the input gear (3, 4).

The invention concerns a toothed-wheel gear change with powerdistribution over several layshafts, a coaxial input shaft radially andaxially supported and an output shaft (main shaft) which is floating,wherein at least one input gear provided upon the input shaft transmitsthe torque to gears meshing therewith and firmly secured to saidlayshafts, the loose gears being axially secured but radially free uponthe input and output shafts.

In transmissions of this kind having at least two layshafts, the loadcompensation is in general such that the input shaft and the layshaftsare rigidly supported with respect to the housing while the main shaftor output shaft is floating in the summation gears situated thereonwhich are in the power flow.

In the presence of two or more constants, the problem arises that in thecase of several input gears the input gear not engaged requires radialplay due to manufacturing tolerances. When a torque diminishes on alayshaft, radial and axial forces result in a helically cut meshing ofteeth on the input shaft. To be able to absorb them, the gear that is inthe power flow must be guided toward the input shaft.

Layshaft gear changes are generally designed in a manner such that theinput shaft is firmly radially and axially supported while the mainshaft or output shaft, on account of the required load compensation, isradially free and only axially fixed. But the inverse design or shaftmechanism is basically possible also.

All loose wheels on the input shaft and on the output shaft are onlyaxially fixed but radially free for a functioning load compensation.

However, the necessary load compensation is disturbed, or an operationof the toothed-wheel gear change is not at all possible, when anasymmetrical intensity of force occurs. This is the case, for instance,when a power take-off has to be effected via one layshaft only. Thismeans that the toothed-wheel gear change of the above mentioned kind isnot suited to such a function.

This invention, therefore, is based on the problem of providing atoothed-wheel gear change of the kind mentioned above which also allowsan asymmetrical intensity of force, especially one where a powertake-off is also possible via one layshaft only.

According to the invention this problem is solved by the fact that theinput gear is radially fixable by a movable securing device.

An asymmetrical force intensity or a one-sided output over one layshaftis possible by radially fixing or centering the input gear situated uponthe input shaft without impairing the operating capacity of thetoothed-wheel gear change.

The securing device will be advantageously coupled with the shiftingdevice for the input gear.

In this manner, a shiftable radial fixing which makes possible twoshifting positions is obtained. At least two input gears are generallypresent, but it is always only the input gear that has to be radiallyfixed for operating capacity. The respective other input gear must beradially free.

However, the number of shiftable fixings is not basically limited.

A simple, practical design of the securing device or of the ramp canconsist in designing the ramps as a diameter reduction of the input gearbeneath which an axial extension of the sliding sleeve is movable forthe axial fixing.

By means of said design, a radial fixing of the input gear issimultaneously provided when coupling or connecting the torque of theinput gear with the input shaft.

In order to obtain a perfect torque transmission and prevent tilting ofthe input gear, it can be provided that the diameter reduction extendsaxially beyond the center of meshing of the teeth.

A very advantageous further development of the invention consists in thesecuring device forming, at the same time, the torque-transmittingdevice.

The torque is transmitted from the input shaft to the layshaft in amanner known per se via a coupling gearing between the sliding sleeveand the input shaft. According to the invention, said gearing is nowsimultaneously used for the centering or radial fixing of the inputshaft.

In a practical development for instance, this results from the securingdevice or the torque-transmitting device being situated in the area ofthe internal peripheral ring of the input gear.

In this case the ramp is practically obtained in the form of a diameterreduction of the internal peripheral ring of the input gear or of acorresponding diameter increase of the gearing situated upon the slidingsleeve.

The securing device or the torque-transmitting device will be hereadvantageously situated in the area of the axial center of meshing ofthe teeth whereby a perfect centering is given and tipping torques areprevented.

In an advantageous further development of the invention, it can beprovided that the selector gears have tooth flanks conically tapering onboth sides.

This design assists the axial fixing of the input gear under torqueload. In practice, taper angles of more than 3° have proved especiallyadvantageous.

The clutch gearing between input shaft and sliding sleeve can bedistributed in different areas. Said different areas each have differentbase tangent lengths. Two different base tangent lengths are preferablyprovided. They are preferably on the input shaft. The different areaswith different base tangent lengths prevent the automatic disengagementof the sliding sleeve from the currently selected shift position.

The securing device is movable in both axial directions or interactswith two input gears.

Two embodiments of the invention are fundamentally described herebelowwith reference to the drawings. In the drawings:

FIG. 1 is a total view of the toothed-wheel gear change;

FIG. 2 is a sectional enlargement of the area with the input gears and asecuring device according to the invention;

FIG. 3 is a sectional enlargement of the unengaged input gears with asecuring device of a different type of construction;

FIG. 4 is an engaged enlargement according to FIG. 3;

FIG. 5 is an enlarged top view of a basic illustration of the gears ofthe securing device; and

FIG. 6 is an embodiment of the sliding sleeve.

The toothed-wheel gear change has a construction basically known per sewherefore only the parts essential to the invention will be discussed indetail herebelow.

An input shaft 2 supported in a housing 1 is connectable with two inputgears 3 and 4, for torque transmission, via a shifting device 5. Theinput gears 3 and 4 are in tooth contact with gears 8 firmly connectedto the layshafts 6 and 7.

As known per se, part of the gears 8 are in tooth contact with loosegears 10 situated on an output shaft 9. The output shaft or main shaft 9is floating.

In order to make possible a power take-off, not shown here, on thelayshaft 6 and the one-sided load decrease on the layshaft 6 connectedtherewith, a securing device is provided for a radial fixing of theengaged input gear. Actually, both input gears 3 and 4 are normallysituated with radial play upon or above the input shaft 2.

According to the embodiment of FIG. 2, the input gear 3 has a diameterreduction in the form of a ramp 12 on its internal peripheral ring. Thediameter reduction or ramp 12 extends from the side of the input gear 3facing the sliding sleeve 13 of the shifting device to the center orsomewhat beyond the center of the input gear 3. The sliding sleeve 13 isguided with scarce play on the input shaft 2 and is connected therewithby gearing 18. The area 19 of the input shaft 2 opposite to the ramp 12of the input gear 3 is likewise designed in the form of a ramp.

The shifting device 5 is provided, in a manner known per se, with aclutch or gear-shifting gearing 14 for each one of the two input gears 3and 4. The sliding sleeve 13 is provided with an axial extension 15. Theaxial extension 15 projects, with play, beneath the input gear 3, theforward end of which terminates before the ramps 12 and 19 in a neutralposition, that is, not engaged.

If in the usual manner, the shifting device 5 is moved in axialdirection, such as to the left, by a shifting fork not shown here, thenthe axial extension 15 of the sliding sleeve 13 moves between the ramp12 of the input gear 3 and the ramp 19 of the shaft 2. The diameterratios between the outer diameter of the axial extension 15 and theinner diameter of the ramp 12, the same as between the inner diameter ofthe extension 15 and the outer diameter of the ramp 19, are selected sothat the axial extension 15 is inserted playfree between the ramps 12and 19. In this manner, during the shifting operation of the shiftingdevice 5 and the coupling combined therewith of the input gear 3, theinput gear 3 is simultaneously radially guided. Via the ramps 12, 15 theinput gear 3 is centered or fixed relative to the sliding sleeve 13which is centered or fixed relative to the input shaft 2 via the ramps15, 19.

In FIG. 3 and 4 another embodiment of a securing device is shown. But ithas basically the same design as the above described securing device.The essential difference consists in that the securing device forms, atthe same time, the torque-transmitting device, or that both devices arecombined to form a unit.

As can easily be understood from FIG. 3, the input gear 3 likewise has adiameter reduction in the form of a ramp 12 in its internal peripheralring. The shaft 2 similarly has a ramp 19. The sliding sleeve 13, inturn, is insertable between said ramps 12 and 19 by a correspondingextension or as a result of its particular configuration. But unlike inthe embodiment of FIG. 2, the torque-transmitting device is, at the sametime, provided in the area of the ramp 12 in the form of the selectorgearing known per se. For this purpose, the ramp 12 has a correspondingtoothed ring 11 and the sliding sleeve 13 a corresponding ring gear 16on its outer periphery.

In FIG. 3 the position of the shifting device, in an unengaged state ofan input gear, is shown in the first place while the embodimentillustrated in FIG. 4 shows the position of the input gear 3 in anengaged state whereby, as can be seen, the radial centering of the inputgear and the torque connection are produced. For this purpose, thediameter ratios of the toothed ramp 12 of the sliding sleeve 13, in thearea where it meshes with the ramp 12, and the parts of the selectorgearing, toothed ring 11 and gear ring 16, are adequately adapted toeach other so that no radial play exists between said parts.

In the arrangement of FIG. 3 and FIG. 4, the radial fixing can bedivided in two components wherein the centering operation is assumed onone by the profile thickness of the selector gearing 14, 11, 16 and ofthe gearing 18 and on the other by the ramps 12, 15 and 15, 19.

As can be understood from FIG. 5, the tooth flanks 17 of the teeth ofthe selector gearing 14 and of the toothed ramp 12 conically taper onboth sides. Said conical selector gearing assists the axial movement andthe meshing of the sliding sleeve under torque load. The taper angle canamount to 3.5°, for instance.

The sliding sleeve 13 can also be designed so as to have extensions 15on both sides which correlate with ramps 12 both on an input gear 3 andon an input gear 4. Corresponding ramps 19 are then also provided on theshaft 2 in the area of the input gears.

Another advantageous design of the sliding sleeve 12 is shown in FIG. 6.

Here the sliding sleeve 13 is divided in two parts. A first part 20 hasthe selector gearing 14 for torque transmission and the axial extension15 for fixing the input gear 3. The second part 21 is positivelyconnected with the first part 20. The second part 21 contains parts of asynchronizing device, known per se and not described in detail here. Thepositive locking between both parts 20 and 21 can be obtained by agearing 22, for instance. Both parts 20 and 21 can be axially secured toeach other by a snap ring situated in a perforation in part 21 andmeshing with a perforation in part 20. The part 21 also can axially abutagainst a projection of the part 20 and be axially secured by a snapring 23 which, on the side of the part 21 opposite the projection,meshes with a perforation of the part 20.

    ______________________________________                                        Reference numerals                                                            ______________________________________                                        1         housing    14        selector gearing                               2         input shaft                                                                              15        axial extension                                3         input gear 16        gear ring                                      4         input gear 17        tooth flank                                    5         shifting device                                                                          18        gearing                                        6         layshaft   19        ramp                                           7         layshaft   20        sliding sleeve part                            8         gear       21        sliding sleeve part                            9         main shaft 22        gearing                                        10        loose gear 23        snap ring                                      11        toothed ring                                                        12        ramp                                                                13        sliding sleeve                                                      ______________________________________                                    

We claim:
 1. A toothed-wheel gear change having a radially and axially supported input shaft and a coaxial and floating output shaft and having a power distribution over a plurality of countershafts, at least one input gear being provided on said input shaft for transmitting torque to gears meshing therewith and firmly connected with said plurality of countershafts, and said torque being transmitted to loose gears being axially fixed but being radially freely movably situated on said output shaft, and said torque being transmitted to said output shaft by way of a respective coordinated coupling device;wherein said at least one input gear is provided on said input shaft, for torque transmission, as an axially fixed and radially freely movable loose gear (3), said at least one input gear is coupled with said input shaft by a shifting device (5) and said at least one input gear is radially fixed, upon engagement of said at least one gear, by a movable securing device (12, 15, 19) which is at least partially located, during said coupling, between said at least one gear and said input shaft.
 2. A toothed-wheel gear change according to claim 1, wherein said securing device (12, 15, 19), for said input gear (3, 4), is coupled with said shifting device (5).
 3. A toothed-wheel gear change having a radially and axially supported input shaft and a coaxial and floating output shaft and having a power distribution over a plurality of countershafts, at least one input gear being provided on said input shaft for transmitting torque to gears meshing therewith and firmly connected with said plurality of countershafts, and said torque being transmitted to loose gears being axially fixed but being radially freely movably situated on said output shaft, and said torque being transmitted to said output shaft by way of a respective coordinated coupling device;wherein said at least one input gear is provided on said input shaft, for torque transmission, as an axially fixed and radially freely movable loose gear (3), said at least one input gear is coupled with said input shaft by a shifting device (5) and said at least one input gear is radially fixed by a movable securing device (12, 15, 19); said securing device (12,
 15. 19) for said input gear (3, 4), is coupled with said shifting device (5); and a ramp (12, 19) is provided on at least one of a sliding sleeve (13) of said shifting device (5) and said securing device (12, 15, 19).
 4. A toothed-wheel gear change according to claim 3, wherein said sliding sleeve (13) is coupled with a ramp (12) carried by said input gear (3, 4).
 5. A toothed-wheel gear change according to claim 4, wherein said ramp (12) is formed as a reduction in diameter of said input gear (3, 4) and an extension (15) of said sliding sleeve (13) is movable for radial fixing said at least one input gear.
 6. A toothed-wheel gear change according to claim 5, wherein said reduction in diameter extends axially beyond a center of a tooth contact.
 7. A toothed-wheel gear change according to claim 1, wherein said securing device (12, 15, 19) also forms a torque-transmitting device (14).
 8. A toothed-wheel gear change according to claim 7, wherein at least one of said securing device (12, 15, 19) and said torque-transmitting device (14) is situated on an inner peripheral area of said input gear (3, 4).
 9. A toothed-wheel gear change according to claim 8, wherein at least one of said securing device (12, 15, 19) and said torque-transmitting device (14) lies in an area of an axial center of a tooth contact.
 10. A toothed-wheel gear change according to claim 7, wherein said torque-transmitting device (14) is provided with tooth flanks (17) which conically taper on two sides.
 11. A toothed-wheel gear change according to claim 10, wherein the angle of tapering of said tooth flanks (17) is at least 3°.
 12. A toothed-wheel gear change according to claim 1, wherein said securing device (12, 15, 19) is at least one of movable in both axial directions and interacting with two said input gears (3, 4).
 13. A toothed-wheel gear change according to claim 1, wherein a clutch gearing (18), having areas of different base tangent lengths, is provided between said input shaft (2) and said sliding sleeve (13).
 14. A toothed-wheel gear change according to claim 13, wherein said areas of different base tangent lengths are situated on said input shaft (2).
 15. A toothed-wheel gear change according to claim 3, wherein said sliding sleeve (13) comprises first and second parts and said second part (21) supports components of a synchronizing device.
 16. A toothed-wheel gear change according to claim 15, wherein said sliding sleeve (13) supports said securing device (12, 15, 19) and said torque transmitting device (14) and said second part (21) are secured to one another by a snap ring (23).
 17. A toothed-wheel gear change according to claim 15, wherein said first and second parts (20, 21) of said sliding sleeve (13) are positively interconnected.
 18. A toothed-wheel gear change according to claim 15, wherein a snap ring (23) axially secures said first and second parts (20, 21) to one another.
 19. A toothed-wheel gear change according to claim 15, wherein said positive interconnection is accomplished by a gear. 